Trinity test site

Trinity was the first nuclear explosion in history. The United States Army set it off at 5:29 a.m. on 16 July 1945, in the Jornada del Muerto desert of New Mexico, about 56 kilometres south-east of the town of Socorro. It was part of the Manhattan Project.

The bomb, nicknamed the 'gadget', was a plutonium implosion bomb, the same design later used on Nagasaki. It released energy equal to about 25 kilotons of TNT. The site lies inside a missile range and is normally closed, opening to visitors only once or twice a year. It was named a National Historic Landmark district in 1965.

Why was it tested?

The scientists were worried that the complicated design might not work, so they decided to test it first. The code name Trinity was chosen by J. Robert Oppenheimer, director of the Los Alamos Laboratory, and it may have been inspired by poems by John Donne. Kenneth Bainbridge planned and directed the test. A steel container named Jumbo was built in case the bomb fizzled, but it was not used. A rehearsal with 108 short tons of explosives took place on 7 May 1945.

What happened and after

About 425 people were there on the test weekend, including famous scientists such as Enrico Fermi, Richard Feynman and Hans Bethe. The blast produced a huge cloud of fallout, and nearby residents were not evacuated. According to the globe card, the blast melted the desert sand into green glass now called trinitite. Later radiation safety rules, developed partly from Trinity data, would have required evacuation at those distances.

On the globe

The model shows the desert test site with the steel tower and the Gadget. It is a restricted place that opens only a few days a year.